During formation of a polycrystalline silicon (polysilicon) layer, which can serve, for example, as a gate layer for a semiconductor device, polysilicon nodule defects can form on the polysilicon layer. The polysilicon nodule defects, which can be as large as the initial thickness of the polysilicon layer, can cause a significant undesirable effect on the integrity of the polysilicon layer. Also, the polysilicon nodule defects can cause unwanted bridging in semiconductor devices, which can be very difficult to remove in subsequent processing steps.
Polysilicon nodule defects can also form on an oxide layer after an overlying layer of polysilicon has been etched. For example, polysilicon nodule defects can form on sidewalls of oxide segments that are situated under a polysilicon layer after the polysilicon layer has been etched to form wordlines during memory device fabrication. Although over-etching the polysilicon layer may remove some of the polysilicon nodule defects, over-etching can also cause undesirable damage to underlying semiconductor device layers.
Thus, there is a need in the art for a method for effectively removing polysilicon nodule defects that are formed on a deposited layer of polysilicon or formed on an oxide segment after etching an overlying polysilicon layer.